In wireless communication systems, antenna arrays are used at devices on one or both ends of a communication link to suppress multipath fading and interference and to increase system capacity by supporting multiple co-channel users and/or higher data rate transmission. In a frequency division duplex (FDD) system or a one-sounding time division duplex (TDD) multiple-input multiple-output (MIMO) wireless communication system, configuring a base station equipped with an antenna array to achieve improved downlink MIMO transmission performance is more difficult than improving the performance on an associated uplink due to a lack of information of estimated downlink channel coefficients. In general, a downlink channel covariance can be used to determine the downlink beamforming weights. However, in many situations an uplink channel covariance cannot be used to compute predicted or candidate downlink beamforming weights.
Current MIMO beamforming weights computation algorithms exist that in general require rather complex calculations, such as those associated with matrix inversions or eigenvalue decomposition. These types of computations use a significant amount of processing capability and consequently can place a significant burden on the computation resources in certain wireless MIMO communication products.
Thus, there is a need for a simpler orthogonal beamforming weight computation method that does not require complex computations such as matrix inversions or eigenvalue decompositions, and still achieve desirable performance levels.